Magnetic and MO media are widely employed in various applications, particularly in the computer industry for data/information storage and retrieval purposes. A magnetic medium in e.g., disk form, such as utilized in computer-related applications, comprises a non-magnetic substrate, e.g., of glass, ceramic, glass-ceramic composite, polymer, metal, or metal alloy, typically an aluminum (Al)-based alloy such as aluminum-magnesium (Al—Mg), having at least one major surface on which a layer stack comprising a plurality of thin film layers constituting the medium are sequentially deposited. Such layers may include, in sequence from the workpiece (substrate) deposition surface, a plating layer, e.g., of amorphous nickel-phosphorus (Ni—P), a polycrystalline underlayer, typically of chromium (Cr) or a Cr-based alloy such as chromium-vanadium (Cr—V), a magnetic layer, e.g., of a cobalt (Co)-based alloy, and a protective overcoat layer, typically of a carbon-based material having good mechanical (i.e., tribological) properties. A similar situation exists with MO media, wherein a layer stack is formed which comprises a reflective layer, typically of a metal or metal alloy, one or more rare-earth thermo-magnetic (RE-TM) alloy layers, one or more dielectric layers, and a protective overcoat layer, for functioning as reflective, transparent, writing, writing assist, and read-out layers, etc.
According to conventional manufacturing methodology, a majority of the above-described layers constituting magnetic and/or MO recording media are deposited by cathode sputtering, typically by means of multi-cathode and/or multi-chamber sputtering apparatus wherein a separate cathode comprising a selected target material is provided for deposition of each component layer of the stack and the sputtering conditions are optimized for the particular component layer to be deposited. Each cathode comprising a selected target material can be positioned within a separate, independent process chamber, in a respective process chamber located within a larger chamber, or in one of a plurality of separate, interconnected process chambers each dedicated for deposition of a particular layer. According to such conventional manufacturing technology, a plurality of media substrates, typically in disk form, are serially transported by means of a multi-apertured pallet or similar type holder, in linear or circular fashion, depending upon the physical configuration of the particular apparatus utilized, from one sputtering target and/or process chamber to another for sputter deposition of a selected layer thereon.
Referring now to FIGS. 1-2, shown therein, in simplified, schematic cross-sectional top and side views, respectively, is an illustrative, but not limitative, embodiment of a conventional in-line, multi-chamber “pass-by” apparatus for treating opposing surfaces of a plurality of vertically mounted workpieces/substrates, which apparatus can, if desired, form part of a larger, in-line apparatus for continuous, automated manufacture of, e.g., magnetic and/or magneto-optical (MO) recording media, such as hard disks, and wherein a plurality of workpieces/substrates (e.g. disks) are transported in a linear path transversely past a plurality of serially arranged chambers each forming a processing/treatment station for performing a processing/treatment of each of the plurality of substrates.
More specifically, apparatus 10, as illustrated, comprises a series of linearly elongated, vacuum chambers interconnected by a plurality of gate means G of conventional design (i.e., respective inlet and outlet gate means Gin and Gout), the vacuum chambers forming a plurality of treatment chambers or stations, illustratively first and second treatment chambers or stations 1 and 1′, each including at least one, preferably a pair of spaced-apart, oppositely facing, linearly elongated treatment sources 2, 2′ (e.g., selected from among a variety of physical vapor deposition (PVD) sources, such as vacuum evaporation, sputtering, ion plating, etc. sources, and/or from among a variety of plasma treatment sources, such as sputter/ion etching, hydrogen, nitrogen, oxygen, argon, etc. plasma sources) for performing simultaneous treatment of both sides of dual-sided workpieces. Apparatus 10 further comprises a pair of buffer/isolation chambers such as 3, 3′ and 3′, 3″ at opposite lateral ends of respective treatment chambers or stations 1 and 1′ for insertion and withdrawal, respectively, of a plurality of vertically oriented workpieces/substrates, illustratively a plurality disk-shaped substrates 4 carried by a plurality of workpiece/substrate mounting/transport means 5, 5′, e.g., perforated pallets adapted for mounting a plurality of disk-shaped substrates/workpieces, for “pass-by” transport through apparatus 10. Chambers 6, 6′ respectively connected to the distal ends of inlet and outlet buffer/isolation chambers 3, 3″ are provided for use of apparatus 10 as part of a larger, continuously operating, in-line apparatus wherein workpieces/substrates 4 receive processing/treatment antecedent and/or subsequent to processing in apparatus 10.
Apparatus 10 is, if required by the nature/mode of operation of treatment sources 2, 2′, provided with conventional vacuum means (not shown in the drawing for illustrative simplicity) for maintaining the interior spaces of each of the treatment chambers 1, 1′, etc. and buffer/isolation chambers 3, 3′, 3″, etc. at a reduced pressure below atmospheric pressure, and with means for supplying at least selected ones with an appropriate process gas (not shown in the drawing for illustrative simplicity). Apparatus 10 is further provided with a workpiece/substrate conveyor/transporter means of conventional design (not shown in the drawings for illustrative simplicity) for linearly transporting the workpiece/substrate mounting means 5, 5′ through the respective gate means Gin and Gout from chamber-to-chamber in its travel through apparatus 10.
As indicated above, according to a preferred embodiment of the present invention of particular utility in the manufacture of disk-shaped magnetic and/or MO recording media, the workpieces/substrates 4, 4′ carried by mounting means 5, 5′ are in the form of annular disks, with inner and outer diameters corresponding to those of conventional hard disc-type magnetic and/or MO media, and each of the illustrated treatment chambers 1, 1′ of apparatus 10 is provided with a pair of opposingly facing, linearly extending physical vapor deposition sources 2, typically elongated magnetron sputtering sources, for deposition of respective constituent thin films of the multi-layer magnetic or MO media on each surface of each of the plurality of disks 4, 4′ carried by the perforated pallet-type mounting means 5, 5′.
Automated manufacture of magnetic recording media, e.g., hard disks, utilizing in-line or circular multi-chamber processing apparatus such as described supra, may require that one or more processing/treatment chambers, e.g., sputtering chambers, contain relatively high pressure sputtering gas atmospheres, for example, ˜30 mTorr. In typical continuous manufacturing systems, such as described above, the sputtering gas(es) is (are) delivered, i.e., flowed, to the respective sputtering chamber before entry of the substrate(s)/workpiece(s) into the chamber, and removed, i.e., pumped out, from the chamber during sputtering and after completion of the sputtering process and withdrawal (exiting) of the substrate(s)/workpiece(s).
A typical sputtering cycle performed in apparatus 10 in the manufacture of multi-layer magnetic recording media comprises sequential steps of:
(1) sputter depositing a layer of a selected material on each of the substrates/workpieces 4, 4′ in respective sputtering stations or chambers 1, 1′, with inlet and outlet gas gates Gin and Gout of each sputtering chamber maintained in a closed position;
(2) evacuating sputter gas(es) from each sputtering station or chamber upon completion of sputter deposition therein;
(3) opening the inlet and outlet gas gates Gin and Gout of each sputtering chamber;
(4) transporting sputter-coated substrates/workpieces 4, 4′, etc. from upstream sputter (or other type) treatment stations or chambers (e.g., 1) to the respective adjacent downstream sputter (or other type) treatment stations or chambers (e.g., 1′);
(5) closing inlet and outlet gas gates Gin and Gout of each treatment station or chamber after entry of substrates/workpieces thereinto;
(6) supplying (i.e., flowing) process gas(es) to each sputtering station or chamber to achieve a desired pressure therein; and
(7) repeating steps (1)-(6) as necessary.
However, in practice, the flow of sputtering gas(es) into the chamber during delivery, as in step (6), and the subsequent pump-out of the sputtering gas(es) in step (2), i.e., upon repetition of the cycle of steps (1)-(6), are both limited by the conductance of the system. As a consequence, an increased interval is frequently required between sputtering of workpiece(s)/substrates carried by successive pallets to the sputtering chamber in order to reach steady-state pressure in the chamber as the sputtering gas(es) is (are) supplied to the chamber. Thus, product throughput rates may be significantly limited by the intervals required for pump-out of a process chamber subsequent to completion of the treatment therein of the substrates/workpieces and prior to re-pressurization of the chamber preparatory to treatment therein of the next group of substrates/workpieces.
Accordingly, there exists a clear need for improved means and methodology for performing a plurality of treatments of substrates/workpieces in automated, continuously operating, multi-chamber, in-line apparatus, wherein substrates/workpieces are carried by a transport means serially through a plurality of treatment stations or chambers. Specifically, there exists a need for improved means and methodology for treating substrates/workpieces in a multi-chamber, in-line manufacturing apparatus at product throughput rates consistent with the requirements for economic competitiveness. More specifically, there exists a need for improved means and methodology for treating substrates/workpieces in a multi-chamber, in-line manufacturing apparatus which eliminates, or at least substantially mitigates, the above-described problems, disadvantages, and drawbacks associated with the conventional means and methodology for supplying and removing reaction gas(es) from treatment chambers during treatment cycles.
The present invention, therefore, addresses and eliminates, or at least substantially reduces the effects of the problems, drawbacks, and disadvantages on product throughput rates associated with the above-described conventional means and methodology for treating substrates/workpieces in in-line, multi-chamber processing apparatus, while maintaining full compatibility with all aspects of automated manufacturing technology, e.g., as utilized in the manufacture of hard disk recording media.